Presentation #209.01 in the session Connecting Magnetic Reconnection across Space and Laboratory Plasmas.
The seventieth anniversary of the first elucidation of magnetic reconnection is rapidly approaching. During magnetic reconnection, a change in the topology of magnetic fields at the smallest length scales facilitates the rapid release of magnetic energy at the largest length scales. What started as a curiosity and an unpopular idea is now regularly measured in solar, magnetospheric, and laboratory plasmas. This grand challenge problem is now recognized to play a key role in eruptive phenomena in a vast array of settings inside and outside the heliosphere with implications for space weather and fusion. The basic foundations of magnetic reconnection theory at small- and meso-scales are well established, yet new insights and groundbreaking results amazingly continue to be discovered. The symbiosis of satellite and ground observations, laboratory experiments, and theoretical and computational research is on no greater display than in studies of magnetic reconnection. In this presentation, major challenges for magnetic reconnection research will be discussed, focusing on theoretical and computational perspectives. On the theoretical side, exquisitely detailed measurements in space and in laboratories challenge theorists to understand the fundamental processes during reconnection at and below where magnetohydrodynamics breaks down. Understanding macroscopic phenomena from the perspective of kinetic theory is a challenge, but also an opportunity. On the computational side, many applications require pushing the limits of the capabilities of even the most modern of numerical techniques, whether through the requirement of realistic plasma parameters or three-dimensional and global geometries. There are microphysical phenomena not captured in magnetohydrodynamic modeling that can greatly impact the macroscale evolution. Moreover, studies of dissipation and kinetic scale energy conversion are now running up against the fundamental limits of the most time-tested numerical algorithms. Potential future directions for reconnection research from the theoretical and computational perspectives will be discussed.